As a process for producing a hydrocarbon oil used as raw materials for liquid fuel products such as a kerosene and gas oil, a method using a Fischer-Tropsch synthesis reaction (hereinafter, also referred to as the “FT synthesis reaction” in some cases) in which synthesis gas containing carbon monoxide gas (CO) and hydrogen gas (H2) as main components is used as raw material gas is known.
As a process for producing a hydrocarbon oil by the FT synthesis reaction, for example, Patent Literature 1 described below discloses a method using a slurry bubble column reactor (a bubble column type slurry bed reactor) in which synthesis gas is blown into a slurry (hereinafter, simply also referred to as the “slurry” in some cases) with particles of a solid catalyst having activity to the FT synthesis reaction (hereinafter, also referred to as the “FT synthesis catalyst” in some cases) suspended in liquid hydrocarbons.
In this method, a hydrocarbon oil is produced by a reaction system provided with a reactor that performs the FT synthesis reaction with accommodating the slurry and having a gaseous phase portion in an upper portion of the slurry (slurry bubble column reactor); a conduit that blows the synthesis gas into a bottom portion of the reactor; a catalyst separator equipped with a filter, that separates catalyst particles from the slurry in the reactor; a conduit that takes out liquid hydrocarbons (heavy liquid hydrocarbons) synthesized in the reactor and passing through the filter; and a mechanism that sends back a part of the liquid hydrocarbons taken out via this conduit to the filter and washes the filter. In the mechanism that washes the filter, a so-called “backwashing” manner is adopted in which the liquid hydrocarbons (heavy liquid hydrocarbons) taken out via the conduit are, for example, periodically flowed to the filter in a direction opposite to the flowing direction of the liquid hydrocarbons when the catalyst particles are separated from the slurry, and the catalyst particles captured by the filter are returned into the slurry again.